A booking app is an application that enables users to make reservations or book appointments for various services such as hotels, flights, transportation, events, and activities. It provides users with an easy-to-use interface to search, compare, and book services, as well as manage their bookings, receive reminders, and make changes or cancellations if needed. The app also often includes features like reviews and ratings, payment processing, customer support, and loyalty programs to enhance the user experience.